1. Field of the Invention
The present invention relates to a file sharing system, a file sharing device, and a method of migrating file sharing volumes.
2. Description of the Related Art
In order to share data between a plurality of computers that are distributed over a network, a file sharing device is employed. As an initial-type of file sharing device, a file server obtained by mounting a file sharing protocol such as CIFS (Common Internet File System) or NFS (Network File System) on a general OS (Operating System) is known. As an enhanced file sharing device, an NAS (Network Attached Storage) that uses a dedicated OS that is specialized for file sharing services and which supports a plurality of file sharing protocols (CIFS, NFS, DAFS (Direct Access File System) or the like).
On the one hand, the number of files to be shared and the number of clients using the shared files is increasing year by year and individual file sizes are also increasing. In order to meet the increase in the demand for such file sharing services, storage devices and communication lines and so forth are augmented or existing file sharing devices are changed to higher performance file sharing devices, example.
As a first conventional technique for performing migration from old file sharing devices to new file sharing devices, a technique according to which a file sharing migration program provided on a new file server is connected at block level to a volume of an old file server and file sharing setting information and volume setting information of the old file server are acquired is known (Japanese Application Laid Open No. 2005-321913). According to this first conventional technique, during the migration, a file access request from the host computer (‘host’ hereinbelow) is issued to the volume in the old file server on the basis of the file sharing setting information and volume setting information of the old file server thus acquired.
As a second conventional technique, a technique that network-mounts a file sharing system of a migration source NAS20 in a migration source storage region provided in the migration destination NAS and transfers data from the migration source storage region to the migration destination storage region in the migration destination NAS is known (Japanese Application Laid Open No. 2005-084963).
As a third conventional technique, a technique that, after transferring the file tree structure from the migration source NAS to the migration destination NAS, converts the file disk repeater received by the migration destination NAS into a file disk repeater for the migration source NAS in order to read the data from the migration source NAS is known (Japanese Application Laid Open No. 2006-039814).
As a fourth conventional technique, a technique that reads data that has not yet migrated to the migration destination file server from the migration source file server and supplies the data to the host is known (Japanese Application Laid Open No. 2003-173279).
The viewpoint that the data migration method is controlled in accordance with the usage state of the migration target volume is not included in either of the above techniques. Hence, irrespective of the size of the frequency with which the host utilizes the migration target volume, data are transferred by means of the same method. Hence, there is the probability of waste in the migration of the migration target volume.
Furthermore, in each of the conventional techniques, a migration destination volume that stores data of the migration target volume is formed on a specified physical storage device as per a normal volume. Therefore, in each of the conventional techniques, the storage resources of the migration destination file sharing device are consumed irrespective of the size of the frequency of use by the host.